Sounds like you need some new sims. Oceanofgames.com has FSX and FS2004 for free. It is a piracy site, but there are no viruses, and it gives you the highest download speed your internet plan will allow. I use it all the time because I'm cheap and I don't wanna spend my money on games. The new Microsoft Flight Simulator 2020 is coming out some time this year, too. It will require you to have some pretty crazy specs, like 150 GB of HDD Space, and 8 GB RAM, but I think it's worth what ever they will charge you for it if you have the specs to run it. Now, if you don't want to get a new sim, here's my opinion.
I wouldn't go with X-plane because the version you have is extremely outdated, and I would say it's only worth X-Plane over MSFS if you have XP10 or XP11. I also wouldn't recommend Fly II, even though it is from the same year as FSX, because it is not a mainstream sim, and addons won't really have much support, and I can't guarantee the server will work either, if you want to fly on it. MSFS 98 is a cool sim, but it is waaaaayyyy too old. You can run it, but it is complicated and won't look very good on a modern PC. Addons, especially non-plane addons (e.g. GPS, other software, etc), are virtually extinct nowadays. This leaves us with just FS2002, which I would recommend if you don't have the specs to run FSX or the new FS2020 coming out. FS2002 is highly supported by my server software, and addons are getting rarer, but they are still quite common on the web. It will also run fairly well on a modern PC. Its built in GPS will also be just fine. If you have FS2004, I would recommend that over '02, but if that's all you got, I would definitely go with FS2002.
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